Mahjong is a tile-based game that was developed in the 19th century in China and has spread throughout the world since the early 20th century. It is played by four players. The game and its regional variants are widely played throughout the Sinosphere in East and Southeast Asia and have also become popular in Western countries. The game has also been adapted into a widespread form of online entertainment. Similar to the Western card game rummy, mahjong is a game of skill, strategy, and luck. To distinguish it from mahjong solitaire, it is sometimes referred to as mahjong rummy.